Is the hard part going to be replacing the guy who replaced Mariano Rivera?

For years, it seemed that Rivera was the most irreplaceable part of the Yankees roster – and long term, he might be — but Rafael Soriano gave the Yankees a reasonable Rivera impression this season. It was an adventure from time to time, but Soriano got the job done. He might not have been The Greatest, but he was one of the best closers in baseball, so good that it actually makes sense for him to opt out of the final year of his enormous contract.

Now it seems that Rivera is not a sure thing to reclaim the ninth inning, and that leaves quite a bit of uncertainty at the back of the Yankees bullpen.

The sense I’ve gotten is that the Yankees still expect Rivera to eventually settle on playing one more season, but that’s not a done deal, and it’s clearly not as certain as it was in May when Rivera vowed: ““I am coming back. Put it down. Write it down in big letters. I’m not going down like this.”

Rivera was not a constant in the Yankees clubhouse this season, and although he did extensive rehab work on his knee, he never made another definitive “I’ll be back” statement.

If Rivera goes against expectation and fades into retirement, would the Yankees spend on a closer? Would they push Dave Robertson into the role? Could they count on Joba Chamberlain and David Aardsma — two guys who had Tommy John surgery in 2011 — to bridge the gap of the late innings. Is Mark Montgomery a legitimate heir to Rivera’s throne, and is he one who could actually live up to that billing?

It seems one thing less certain than entering a season with a 43-year-old closer is entering a season without one.